Selective control system



A. u. s'A'nNMARK.

SELECTIVE CONTROL SYSTEM.

APPLICATION FILEUSEPT-9, 1916.

f if* e; 015 5 f a T- In venfofr A. u. SRNMARK. SELECTIVE CONTROLSYSTEM.

APPLICATION FILED SEPLS, |916- Patented'luly 27, 1920'- s SHEETS-SHEETs'.

AXEL UNO SRNMARK, or STOCKHOLM, SWEDEN.

sELEoTrvn CONTROL SYSTEM.

Specification of Letters Patent.

Application filed September 9, 1916. Serial No. 119,196.

ToV all whom t may concern:

Be it known that I, AXEL UNO' SRN- sunk, a subject of the Ising ofSweden, re-

siding at Stockholm, in the Kingdom of Sweden, have invented a new anduseful Imor without the earth as return conductor.

he invention is primarily intended Jfor telegraphing type-writing, butit may also be used for operating' signal devices, ior'igniting minesand for other arbitrary purposes when it is required to effect from' a.distance a desired adgustinent or regulation.

The invention-is broadly characterized by this that at the sendingstation means are provided for sending tothe receiving station positiveas well as negative pulsations in variable sequence and'number, while atVthe receiving' station there is provided'at least one relay or the likeadaptedY to be actuated by the positive pulsations (so-calledplus-polarized relay), and atleast one relay or the like adaptedtobeactuated by the negative pulsations (minus-polarized relay),whichrelays leffect/the closing and breaking- O' diiferent'local circuits atthe receiv 'very important advantages. c In the first place its functionisindependent of the resistance in the conductor ybetweenv the ,twol

stations and thus to certain extent of the strength or".`A the currentinthe conductor', provided oi course that the Ycurrent is suiicient toroperating the relay.` Moreover, by us lpositive as well as negativepulsations the advantage is attained that the line conductor.

g station, according' to the sequence and the number ci the positive andnegative always becomes discharged again, hence the pulsations mayfollow closely to each other, so that the transmitting of the signalsmay take place exceedinglyv rapidly and surely even with long lines withcomparatively great capacity. f

I In the accompanyingV drawings a few embodiments of the presentinvention have been shown diagrammatically by way of example. Figure .lthe immediate purpose of which is to illustrate the very fundamentalprinciple of the invention, shows an'a'rrangement r'or signaling at aAdistance with the use of a single conductor and the earth as returnFigs. 2 to 5 show some jminor Patented July 27, 1920.

modifications of the receiving station of this .Y

arrangement. Fig. 2 shows a parallel connection of tle plus-polarized'and minuspolarized relays, Fig. 3 showsa vconnection for using onlyoneplus-polarized relay at this station, Fig. 4 shows a modification of vthe connection according to Fig. 8, and Fig. 5 shows a furtherconnection for using only one plus-polarized relay at the receivingstation without any additional local battery. Fig. 6 illustrates how theinvention may suitably be applied for telegraphing typewriting with theuse of a double conductor (for instance two telephone wires) and theearth, in the place of which latter a third wire may, of course, also befused if desired.

Referring to Fig. l, A denotes a sending station and a'receiving stationwhich stations are connected with one another by means of a single-wireconductor l with the earth as return conductor (or by means ofdouble-wire conductor if desired). At the sending station the embodimentillustrat-ed is provided with three elements for giving signals, shownas keys I, II, and III, to which correspond three receiving elements I',II, and III at the 'station B.

rIhese receiving elements are here supposed to consist of smallincandescent lamps, elecr tromagnets or the like. At the sending stationthere is further provided a battery 2 'the middle point of whichi'sgrounded, and

a rotary contact drum 8 (which is supposed to be cut open on the lineC-D and is shown developed). The contact drum is made of insulatingmaterial and in the surface of the same Va number' of conductive'members are embedded. Two of these inembers consist of rings l and 5around the drum, the former of which is provided with short laterallyprojecting bar 6, the other lOO members consisting of a number of bars,7 to 13, parallel to one anotherL and to the aXis of rotation of thedrum".Y Every second of these bars, viz. 7, 9, 11, and 13 which are ofdecreasing lengths are connected withV one another and with the ring 4while the other bars 8, v10, and 12 which are of the same length, areconnected witheachother and with the ring 5. A. plurality of contactbrushes 14 to 21 bear against the surface ofthe drum, the two latter ofthese brushes not being included, however, in the connectionillustrated. rhe brush 15 is connected to the positive pole of thebattery 2, while the brush 17 is connected to a point 'of the batterybetween its middle point and its negative pole, on account of-whichthe.Y

ring 5 and the bars 8, 10, and 12 connected to the saine'will alwayscarry a weak negative tension.V At' the sending station there areprovided three relays 22, 23, and 24 with armatures 25, 26, and 27 thefunctions of which will be further explained here below.

. The negative pole of the battery 2 is connected to the working contactof the armature 25,- the armature itself being connected to theconductor 1. l

At'the receiving station Bthere are provided, in addition tothereceiving devices mentioned above, a local battery 28, a minuspolarizedrelay 29, two.plus-polarizedrrelays +30 and +31, and non-polarizedrelays 32, 33, 34, 35,7and finally a relay 36 which may be eithervpolarized or non-polarized,

preferably' polarized, however. All these relays are provided witharmatures 37, ,33,V

39,. 40, 41,142, 43, and il, respeeuveiy. The conductor 1 is connectedto Vthe armature 40.

'The windin'gof .the relay 36 is connected with' thesecondary Vwinding45 of' an induction coil, the primary winding 46 of which is connectedbetween the armature 37 and the lamps I', II', and III. y

`When operating the arrangement, the contact drum 3 rotates all the timein the direction indicated by the arrow. If'it is desired to-cause thelamp I at the receiving station to light the key I is pressed down whichonly effects a single contact.

lVh'en at the rotation of the drum 3 the brushl comes into Vcontact withthe bar 6, the following circuit will therefore becomel closed:

from the positive poleY of the battery v2 through the brush 15, the bar6andthe ring 4, the brush.16, the relay 24, and the pressed-down key Itothe middlel point of the-battery. The relay 24 is thus excited andattracts its armature 27 against its i working contact, which causes thefollowf ing new circuit torb'ecome closed: from the positive pole Aofthe battery 2 through the armature 27, the relay 24, and the key I tothe middle point of the battery.y The lrelay 24 thus locks itself aslong as the key I is pressed down. At the same time' the bars vthe'key Ito the middle point of the battery. Both ,relays 23 and 22 thus becomeexcited, and attract their respective armatures 26 and 25. The relay 23hereby locks itself, so that the current passes from the armature 27through the armature 26, the working Y Ycontact of this armature, andthe relay 23,

to the Yrelay 22 and through the key I to the middle point of theybattery'. On account of the attraction of the armature 25 a nega- Itive'current' may flow from the negative' pole Aof the battery 2 through theworking contact 47`of the armature 25, and through the armature 25 tothe'line 1. y

At the receiving station this negative current reaches the larmature 40(of the relay 32) andp'asses'from this armature tothe plus-polarizedrelay +30, which does not 'become attracted by this negative current,

and throughthe'condu'ctor 48 to the minus- Vpolarized relay '29 andV tothe earth. The

armature 37 ofpthis relay thus becomes attracted, on account of ,which acircuit becomes closed from thelpositive pole of the batteryV 28,throughv the arma-ture 42, the lamp I, thel primary' winding 46,4 andthe armature 37, to theA battery 28. The lamp I is thus madel to light.v r

j'When. the key I at the sending station ,A `is released', the'circuitsv through the. re-

Vlays 24, 23, and 22 become broken, and the armatures' of these relaysbecome released. 0n account hereof the negative current becomesbroke'nat 47. On' account of the breaking of the negative current thearmature 37 of the relay +29 at the receiving station ,isV released,hence the local circuit to the lamp I becomes broken andthe lampgoesout. ,n Y

When a negativev current is sent out from 'thesendin'g'station A to theline 1 the lamp I"a't the receiving stationB is thups'lightedV and itwill remain burning asv long as the current lasts. I y Y Y' If, on theother hand, a signal of' the lamp VII is'desired, tlie'keyvII at thesending stationk ,Ay is ,pressed` down. comprisesV two pairs of contacts49 and 50,

rthe pair 49A of which corresponds' to the key I.' By pressing down thekey II, that isu to say by closing these two pairs of contact, it isfirst attainedat lthe rotation of the'conta'ctf drum 3, Ain thesamemanner as Vdescribed above, that the relay: 24 be- This key Vtivetension.

vthe armature 37, to the battery 28.

comes excited and locks itself so that the ring 4 and the bars 7, 9,etc.,'obtain a posilihcn 'at the continued rotation of the drum 3 thebrush 18 now comes into contact with the bar 7, a positive pulsation maythus flow from the positive pole of the battery 2, through the armature27, the'brush'l, the ring 4, the bar 7, the brush 18, the pair ofcontacts 50, the conductor 51, and the armature 25, to the line 1. Whenat continued rotation of the contact drum 3, the brush 14 comes intocontact-.with the bar 6, the relays 22 and 23'become excitedin the samemanner as described above, on account whereof the armature 25 will beswitched into contact with the working contact 47. A. negative pulsationthenv flows from the negative pole and the armature 25, to the line 1;By pressing downthe key 1I a positive pulsatlon will thus be sent out tothe line 1 and afterward a negative pulsation.

by this positive pulsation, and to the ground.

(Ewing to the 1 excitation of the plus-polarized relay +30 its armature38 becomes attracted, so that a circuit 1s closed from the "positiveVpole of the battery 28, through the armature 38, the relay 34, thearmature 44,

.terv 23. The relay 34 hereby locks itself.

llvhen the positive pulsation ceases, and the armature 38 of the relay+30 is released,

a new circuit isrtherefore formed from the battery 28 through thearmature 42, the

contact 52, the armature 38,therelay 32, the

arma-ture 44, to the battery 28, whereby the relay 32 becomes excitedand its armature 40 becomes attracted. The incoming negative pulsationwill then pass through the armature 40, the contact 54, the armature 41,the plus-polarized relay +31 whichdoes not become actuated by the same,the conductor 48, and the rminus-polarized relay -29'to the ground.`Hereby the armature 37 becomes attracted so that al new circuit isformed from the battery 28, the armature 42, the contact 53, thearmature 43, the lamp Il', the primary winding 46, and The lamp H. isthus made. to burn.

ll'vhen the key Il at the sending station A is released, the circuitsthrough the contacts 49 are broken in the same manner as forthe `key l,so that the relays 22,23, and

'24, become demagnetized, on account of which the negativecurrent'becomes broken broken and the lamp goes out.

When the circuit through the lamp II and through the primary winding 46becomes broken current is generated at the moment of breaking inthesecondary winding` 45, v

which current passes through the` relay 36. As stated above, this relayis preferably polarized, and in such case it is polarized in suchmannerthat it becomesactuatedA by the current generated in the secondarywinding 45 when thecurrent in the primary of theV battery7 2, throughthe contact 47,"

winding'46 becomes broken, not-however by the current generated in thesecondary winding 45, when the current 1s closed 1n the primary winding.46. 1t is of course not necessary, however, that the relay 36 bepolarized, as the current induced in theseclondaryv winding 45 becomesless when the current in the primary Winding 46 is closed, than when itis broken, and the relay 36 might therefore be adjusted in such mannerthat it would only lbe caused to operate by the stronger currentgenerated When the current in the primary winding 46l is broken. Ti'vhenat the breaking of the" current through the primary winding 46 a currentof short duration flows through the relay 36, this relay becomes excitedand attracts its armature 44. The circuits through the relays 32 and 34thus become broken so. that their armatures 40 and 42 return to theirnormal positions. All apparatus at the receiving station B are then inthe positions which they assumed before the positive pulsation reachedthe station. V By pressing down the key II atthe sendingstation A ashert positive pulsatin and a long negative pulsation are'thus sentoutthrough the line 1, whichv pulsations cause the lamp Il at thereceiving stationv B vto burn as long as the key H is pressed down. Whenpressing down a key the positive pulsations, if any, always becomeshort, while the negative pulsation or current lasts as long as the keyis pressed down,this being the pulsation operating the signal selectedby the positive pulsations. Y

y 1f lthe vkey HI at the sending station is pressed down, itis firstattained, when the bar 6 passes the brush 15, that the relay 24 becomesexcited, and locks itself, inthe manner above described with referencevto the keys l and 1I, so that the ring 4 and the bars 7,V 9, 11, 13obtain a positive tension. Jl/hen on the continued rotation of the drum3 the brush 19 is passed by the bars 7 and 9, two positive pulsationsymay iiow from the positive pole of the battery 2,

throughthe armature 27, the brush 16, the

ring 4, and cross connection between the latter and bar 7, through oneof the bars 7 and 9, to the brush 19, ,the right-hand pair of contactsot the 'lreylIL the conductor 5l, and the armature 25, to the line 1,Yin similar manner as abovedescribed with reterenceto the key H. Afterevery positive pulsation a negative pulsation is sent out througlrthebrush 19k when itis passed by the bars 3 and lO, which, as previouslydel scribed, are connected to the ring 5 which 14 is passed by the bar46, the relays 22 and willbecome excited in the same manner,

andthesaine circuits will be formed, as

`above explained with reference to the keys l and H, with the exceptiononlv that the leift-hand contacts ofthe key HI are included in thecircuits, instead of the contactsA of the Vkey I Yoi the contacts 49 ofthe heyll. As above described, the armature of the relay 22 will beswitched into contact .with the working contact 47, and a v*negativecurrent will flow from the negative pole ofthe battery 2, through thecontact 47, and the armature 25, to the line l,

HI is pressed down. Y,

The rst Vone of the positive pulsations which current will last as, longas the key feifects Iatrthe receiver station B the. switch-y -ing of therelays +30,. 34, and 32, as described above. The second positivepulsation then iiows through the armature 40, the contact 54, to thearmature 41, and through the plus-polarized relay +31,

' which will then attract its armature 39.

Hereby the armature v43 of the relay Y35 becomes attracted in the samemanner as described above for the lamp H', and when Vthe pulsationceases-the armature 4l ot the relay 33 becomes attracted.` Thelincomingnegative` pulsation then flows through thearmature 40,thecontact 54, the armature 4l, the contact 55, the conductor 56, theconductor 48, and the minus-polarized relay 29, to the ground. Hence acircuit will be closed trom the battery VV.28, through the armature 42,ture 43, the'contact 57,7the armature 58, the lamp III', the primarywinding` 46, and the armature 37, tothe battery, thus making the lamplight. Vhen the key III at the `or signal receivingedevices.

the contact 53, the arma-V sending station A is released, the lamp HIgoes out inthe same manner as described with respect of the lamp H.A p

rlhe sending station A as well as the receiving station B may of coursebe arranged.

tor a practically unlimited number of keys,

ThisV is indicated in the drawing at the sending station A by meansofthe brushes 2O and 2l, and at the receiving station B by ineansof the`armature 58 corresponding for the next lamp to the armature V43V forthe lampA H.

The conductor 5G corresponds for the'next lamp to the circuit throughthe armature 4l and the plus-polarized relay +31 for the lamp III. f Y

Figs. 2 to 5 show a few modifications oit the arrangement of thereceiving station B in Fig. l, each of these igures showing vanalteration'otthe connection below the lines E, F, Gr, and H in Fig. l;Fig. 2 shows Va parallel connection instead of a series connection ofthe plusfpolarized and minus-V vpolarized relays. An incoming positivepulsation from the line l flows 4in this caseV partly through E to therelay 29 Vwithout 'actuating it, and Qtlirouglif F to the ground,

and partlythrough H 4to* the relay +30,

j which becomes excited, and through the armature and through G to theground. It still another positive pulsation comes in beforer thenegative pulsation this positive pulsation alsoflows partly through E,the

relay 29, and F tothe groundand partly through H, the relay +31, thearmature. 4l, the contact 54, andthe armature 40 through G to theground. The negative pulsation in this case flows through Hand theplus-polarized relays, which do Anot become actuated, and through GrV tothe ground, and

besides through E to the minus-polarized` relay 29 and through F totheground.

Fig. 3 shows an arrangement according to which `only one pluspolarizedrelay is used at the receiving station B. In this casethe plus-polarizedVrelays Y+30 and +31 in Fig. l are substituted byvordinary non-polarizedrelays. The Vline Vlis connected to a pluspolarized relay'+59. Thisrelay will thus not become actuated bya negative ,pulsa tion, butsuclipulsation flows through the relay and through F tothe relay 29 andbach through E to the ground, the armature 37, of course,becomingattracted. 'It

V the negative pulsation is preceded by a positive pusation, on theother hand, the armatureGO of the relay +59 becomes attracted,

the relay 29 remaining unactuated. Qwing to the attraction of thearmature 60 a local circuit is closed from the battery 6l, through thearmature 40, the 'relay 30 (which is ynow non-polarized) through H andthe armatureV 60 toth'e battery.V Owing Y to the excitation of the relay30 the circuits Y through the relays 32 and 34 become closed in the samemanner as described above. a second positive pulsation comes inimmediately afterward this'p'ulsation will again attract the armature60, on account whereof a current is again sent outfrom the battery 61,which current in such case flows through the armature 40, the contact54, the armature 41, the (non-polarized) relay 31, and through H and thearmature 60 to the battery. At the subsequent negative pulsation thelamp III will be made to glow.

Fig. 4 shows the alteration to Fig. 3 that the local battery 64 isconnected in series with a resistance 65 between G and I-I` and inparallel with the armature 63 of the pluspolarized relay +62. Thearmature 63 normaliy short-circuits the (non-polarized)l relay 30 sothat practically no current from the battery 64 flows through the same.When the armature 63 becomes attracted by a positive pulsation throughthe relay +62, however, the short circuit through 63 becomes broken andthecurrent from the battery 64 excites the relay 30 in the same manneras for Fig. 3. The advantage of this arrangement as compared with thatshown in Fig. 3, is of course decreased sparking inthe contact, as thecircuit through the battery does not become broken, but only theshort-circuit.

Fig. 5 shows an arrangement according to which only one polarized relayis used at the receiving station, without any additional local battery.An incoming positive pulsation excites the plus-polarized relay +66 sothat the armature 67 becomes attracted, whereby the positive pulsationwill'iiow through H and, as described above, excite the relay 30,v

which is not now plus-polarized. A vsecond immediately followingpositive pulsation will excite the relay 31. The negative p ulsationwill not influence the relay +66, how ever, but iiows through thearmature 67 of the same and through F to the minuspolar- Fig. 6illustrates an arrangement in which two line wires, orinstance twotelephone wires, and the earth, or instead of the earth a third wire,are used for transmitting the pulsations from the; sending station A1 tothe receiving station B1. This arrangement is particularly intended forVtransmitting type-writing. drawing, however', only nine keys have beenshown at the sending station, and at the receiving station only nineelectromagnets for operating nine keys of the typewriter. In order tomake Fig. 6 more perspicuous the references in the same correspond tothereferences 'used 1n Fig. 1, so that for instance the part in Fig. 6corresponding to the part 4 in Fig. 1 has been referenced 104, the partcorresponding to the part 16 is'referenced 116, theA key II correspondsto the key II,

and so forth.

' the relay 122,k

In order to simplify the At the sending station A1 there is. provided,as at the station A in Fig. 1, a battery 102, a contact drum 103 withringsy and bars 104 to 109, and brushes 114 to119, relays 122, 123, 124,with armatures 125, 126, 127,

and keys In, IIa, IIIn which are arranged as the keys I, II, III in Fig.1, and through the latter two of which positive pulsations maybe sentout lthrough the conductor 151 to the line 101. There are further keysIV?" to IX which are arranged in groups 'of three, IVY to VI, and VIIato IXa, in the same manner Y relay 222 is not provided with any workingcontact corresponding to thecontact 147 of on account whereofno negativepulsation can -low to the line 201 apart from those weak negativepulsations which follow every positive pulsation andwhich serve only fordischarging the line but which cannot actuate any apparatus at thereceiv-y ing station.

In the same manner as for Fig. 1, when the key Ia 1s pressed down anegative pulsation flows out into the line 101, when the key IIa ispressed down one positive' and one"l negative pulsation, and forthe keyIIIa two positiveand one negative pulsation` in theline 101. IVhenpressing downfthe keys IVa, Va, and VIa the same pulsations arerespectively obtained in the line 101, but for each key a' positivepulsation is simultaneausly obtained in the line 201, as will be easilyunderstood `from the drawing. IVhen as I1 to ma, with y the differenceum they j tov pressingV down the keys VII?, VIIIR, and

IXa the same pulsations are also obtained in the line 101 as forthekeys-la, II?, and

l IIIa respectively, but at the same time two pulsations are obtained inthe line 201-for each key. Thus foreach key a different combination .ofpulsations in the line con` ductors 101 and 201 is obtained. For theline 101 .there are provided at the receiving station B1apparatus-Ycorresponding to those ,at the station B in Fig. 1, viz.'

' a battery 128, a minus-polarized relay 129,

two plus-polarized relays +130 and +131, non-polarized relays 132.133,134, and 135,

and a relay 136, preferably butinot necessarily polarized, all theserelays being provided with armatures 137V to 144. Each of the relays 134and 135 is hereprovided 7with a pivoted contact 342 and 343,respectively. There will also be found` in the drawing a pivoted contact358 being a corresponding contact in the next group of relays. Thesethree contacts are normally in contactwith conductors 175,176, and'177,respectively, to each of which one pole of threeof ,the magnets 1"? toIXa is connected,as shown in the drawing. `In the circuit of the relay136 the secondary `Winding 145 is connected,

129, and n o plus-polarized relays are re-" quired, but all relays'230,231, 232, 233, 234,V and 235 are non-polarized.` ln other respects thearrangement of the relays and circuits provided for the line 201corresponds to the arrangement at'the station B in Fig. 1 and is similarto the arrangement of the relays Y 'and circuitspiovided 'for theline101. The relays are provided with armatures 236 to 243, the tivo latterrelays being provided with a-pivoted contact 442-and 443, respectively.rFliese contacts and the corresponding pivoted Contact 458 of the nextgroup of relays are'normally incontact With conduce tors 275, 276, andV277, respectively, corre-vw sponding t'o the conductors 175, 176, and177, as shown in the drawing. f

If a single negative pulsation comes in' from the line 101 the differentgroups of relays remain unactuated, but the relay F129 becomes 'excitedso that the local current .from the battery 128 will flow to theconductor 175. If the negative pulsationl is preceded by a positivepulsation the armature 142 and cont'act342l of the relay 134 will beswitched against the contacts 152 and 153 and the negative pulsa'tionivill pass through -the armature 140, contact 154,

arma-ture 141, relay +131, and'relay'-129, l in similar,mannerl asdescribed ivith rete'rence to Fig. 1 and the operationof relay 34V byrelay +30 by a 'positive pulsation and relay -29 by a negativepulsation, when the current from the battery-128 will flow through thecontact 342, the contact 153, and the armature 343, to the conductor176- If tlienegative pulsation is preceded by two positive pulsationsinthe line 101 ,the current from the'battery 128 will Viioiv to theconductor 177 through the armature 137, contact 342, contact 153`contact 343, and contact 358, the operation of the relays +130, 134,132, V+131, 135, ies, and 129, and the circuits formed vbeing similar tothose described with reference to Fig. land the sending of the currentfromA the local battery 28 through the lamp 1H. The

`pulsations sent out through the line 101 will thus determineth'econductor 175, or 176, or 17 7 tow'hichthe positive pole 'of the battery128 Will be connected. When one oi" the keys I, Iva, and VIP at thesending VstationV is pressed down the local current at the receivingstation Will thus-'flow to the conductor- 175, for either of the keys11, Va, or VIHri it will flowv to 176, and for either of Illa, VP or IXato 177; VWhich one o1' 'the 4 magnets 1 to Y@[Xa'ivill become excitedevidently depends `upon through which of' the conductorsV 275, 276, and277 the localv current can return to the battery 128. 1r" no pulsationhas been sent out on the line 201, but the apparatus vconnected to thisline" occupy the positions shown, the current may evidently returnthrough: the` conductor 275 and the contact 442 tothe battery.

The arrangement of the relays and -circuits provided for the line 201being similar to'thosepr'ovid'ed for the line 101 and to the Y WhichclosesV the circuit Vof the relay 234,

Which attracts'its armature 242 and locks itself. The pivoted contact442 is thus switched over against the contact 253, so that connection isestablished between the negative pole of lthebattery 128 and theconductor 276 through 'contact 442, Contact 253, and contact 443.Simultaneously, the connection between the conductor 275 and thenegative pole o1 the battery is broken at the contact 442, 'If only 'onepulsation lis sent out onvthe line 201 the conductor 276 will thus beconnected with the battery.'

232, which attracts its armature 240. lf'a second pulsationis'sentout-on the line 201 such second pul'sationivill thus pass througharmature 240 -to armature 241 and through relay 23,1, ivliichattractsits ariiiatui'eY23),` which closes the Ycircuit Vof the relay 235,

which attracts its armature 243 and' locks itself,^breaking theconnection between the pivoted contact 443 and the conductor 276 andestablishing connection between the conductor 27,7 and the negative poleof Ythe'battery-128 through contactv 458, contact'443, contact 253, andcontact 442.v l

When depending on .the pulsations sent out, the local current may only110W into oneo'f'the conductors 175,176, and 177, and

only return through 'one o'tthe conductors Y For this purpose thereceiving station must of course be provided With a corresponding numberof groups of relays, that is to say six groups or each line. p v

It Will be understood that the plus-polarized relays +130 and +131, andso forth, may be substituted by non-polarized relays by providing asingle relay as shown in Figs. 3, 4 or 5.

The armatures of the polarized relays may either be permanent magnets orbe niagnetiaed by a separate source of current. All relays may bemembrane relays or spring relays or other rapidly operating relays.

l claim: v i

l. ln a selective controlsystein, the coinbinationot means at thesending station for sending to the receiving station positive as Well asnegative pulsationsin variable sepolarized relay at the said stationadapted.

to be actuated by pulsations of the other polarity and controlling thesaid source of current so as to connect the saine to the receivingapparatus selected by the irstnamed relay, substantially as and for thepurpose set 'forth.

i2. ln a selective control syste'nnthe com- Vbination ot means at thesending station for t sendingto the receiving station positive as wellas negative pulsations in variable sequence and number, an electricalconnection between the sending station and the receiving station,receiving apparatus at the receiving station, at least one relay atthereceiving station adapted to be actuated by pulsations of onepolarity, a circuit arranged to be closed by the said relay when itreceives a pulsation of this polarity, asecond relay in said circuitadapted to break a coiinection to one receiving apparatus when the saidcircuit is closed and to establish connection to second receivingapparatus, a second circuit controlled by the said relays and arrangedto be closed when the pulsation in the ifirst relay ceases, a thirdrelay iiisaid second circuit arranged when the circuit is closed to opena connection to a third receiving apparatus, a source of current at thereceiving station, and at least one relay at the said station adapted tobe actuatedrby pulsations orn the other polarity and con` trolling hesaid source of current so as to connect the same to the receivingapparatus selected by the first named relay,- substan- Y receivingstation, receiving apparatus at the` receiving station, at least onerelay at the receiving station adapted to be actuated by pulsations ofone` polarity, a circuit arl ranged to befclosed by the. said relay whenit receives a 'pulsation othis polarity, a sec-A ond relay in'saidcircuit adapted to break a connection to one receiving apparatus when ytiie said circuit is closedV and .to establish" connection to a secondreceiving apparatus,

a second circuit controlled by the said relaysY and arranged to beclosed When the pulsation in the first relay ceases, a third relay insaid second circuit arranged when the circuit is closed vto `open 'aconnection to a third receiif'ing apparatusa source ot current at thereceiving station, at least one relay at the said station-adapted to beactu-- ated by pulsations of the other polarity and controlling the saidsource ofcurrentvsoas to connect the same to the receiving appa-V iatusselectedr by the Iirst named relay, an induction coil the primaryWinding of which is connected iii the circuit of the saidy source orcurrent, a relay connected in the circuiti oj the secondary Winding ofsaid induction coil, said relay controlling the said first and secondcircuits established through the excitation oif the relay ot' the.lirst'polarityfand adapted to break the saine when at theCeasing oit the`pulszfitioiithrough the relay oi the other polarityiand at theconsequent break-V ing ot' the circuit throughthe receiving apparatus acurrent is induced in the secondary Winding at. the moment oit-breaking,

substantially as andl 'for the purpose setv forth.r f l ,Y Il. ln alselective control system, the conibiiiation `ofi-an electric`connection bet-.veen. c

contact drum, contact rings on said drun'i,

contact bars on said drinn, brushes bearing against the said drum, keysvprovidedl i with'y contacts connected With the said brushesa;v

circuit comprising tivo or the brushes and connected tocoiitacts at thekeys in suoli manner as to become closed Avvlien any of the keys ispressed down, arelay invsaid circuit. a source ofcurrent, a connection'from one pole of the said source of current to thel contact barscontrolled by thesaid relay in-y sucli manner that when closedV by--thesame i sequence and the number of the positive and negativepulsations,substantially as and Ifor the purpose set forth. v

5. In a selective control system, the conibina'tion of anelectricconnection between the sending station and the receivingstation, means at the sending station for sending 'to the receivingstation positive as well as negative pulsations in variable'sequence andnumber, said means comprising a rotary contact drum, contact rings onsaid drum',

contact bars on said drum, brushes bearing against the said drum, keysprovided with contacts connected withV the said brushes, a circuitcomprising two Vof the brushes and connected to contacts at the keys insuch manner as to become closed when any of the keys is pressed down, arelay in said circuit, a source of current, a connection from one poleof the said source of current to the contact bars and controlled by thesaid relay in such manner thatwhen closed by the 'same pulsations or acertain polarity may flow through these barsY and through the brushconnected with the key pressed; down to the connection between thestations, a Vsecond circuit adapted to be closed by the said Arelayatera certain interval Vof time, a sccond Vrelay in said second circuitadapted to breakthe connection for the said pulsations from' the saidcontact bars to the connection between-the stations and to connect theop- Y posite pole of the said source or current to the said connectionbetween the stations, at least onerelay at the receiving` stationadapted to beactuated by positive pulsations, at least one relay at thereceiving station adapted'to be actuated by negative pulsations,receiving apparatus at the receiving station, and circuits controllingthe said receiving apparatus and adapted to be closed and broken bymeans of the said relays according to the sequence and the number or thepositive and negative pulsations, substantia'lly as and for the purposeset forth.

6. In a selective control system, the com bination of an electricVconnection between the sending station and the receivingr station, meansat the sending station Jfor sending to the receiving station positiveaswell as negativep'ulsations in variable sequence and number, saidmeanscomprising a rotary contactV drum, contact rings on said drum,

contact bars on said drum, brushes bearing against the said drum, keysprovided with contacts connected with the said brushes, a circuitcomprising two of the brushes Vand connected to contacts at the keys insuch manner as to becomeclosed when any 'of the keys is pressed down,'arelay in said circuit, a source of current, a connection from one poleof the said source of current to the contact bars and controlled by thesaid relay in such manner that when closed by the same pulsationsof acertain polarity may flow throughrthes'e bars and through the brush sconnected with the key pressed down to the connection between thestations, bars on said roller between the said contactbars and con-Anected with a. weak polarity opposing the polarity supplied to the saidcontact bars, Va secondcircuit adapted to be closed by the said relayafter a certain interval or' time, a second relay in said!Y secondcircuit adapted to break the connection forv the said pulsations fromthe said contact bars to the con Y nection between the stations andl toconnect theopposite poleof the said source of current to the saidconnection between the stations, at least one relay at the receivingstation adapted to be actuated by positive pulsations, at least onerelay at the receiving station adapted to be actuated by negativepulsations, receiving apparatus at lthe receiving station, and circuitscontrolling the said receiving apparatus and adapted to be closed andbroken by means of the said relays according to the sequence and thenum-V ber of the positive and negative pulsations7 substantially as andfor the purpose set forth.

7. ln a selective control system, the coinbination of two electricconnections between the sending 'station and the receiving station,means at the Vsending station for send ing to the receiving stationpositive as well as negative pulsations in variable sequence and number,said means comprising a rotary contact drum, contact rings on said Ysuch manner as to become closed when any of the keys is pressed down, Varelay in said circuit, a source of current, a connection from onepole'of the said source or current to the contact bars and controlled bythe said relaypin such manner that when closed by the same pulsations ofa certain polarity may iow through these bars and through the brushconnected with the key pressed down toboth connections between thestations, a second circuit adapted to be closed by the'said relay aftera certain interval of time, a second relay in said second circuitadapted to break the connection for the said pulsations from the saidcontact bars to one of the connections between the stations and toconnect the opposite pole of the said source of current to the 1saidconnection between the stations, a third relay in the said secondcircuit adapted to break the connection for the said pulsations from thesaid contact bars to the other connection between the stations,receiving conductors at the receiving station, receiving apparatusconnected between the said receiving` conductors, at least one relay atthe receiving station connected to the first named connection betweenthe stations and adapted to be actuated by pulsations of one polarity inthe same and controlling half the number of the said receivingconductors for selective connection of the same according to the numberof pulsations of this polarity, means at the receiving station connectedto the other connection between the stations and controlling the otherhalf number ofthe said receiving conductors for selective connection ofthe same according to the number of pulsations in said secondconnection, a source of current at the receiving station, and at leastone relay at the receiving station adapted to be actuated by pulsationsof the other polarity in the first-named connection between the stationsand controlling the said source of current so as to connect the same tothe receiving conductors selected by the iirstnamed relay and by thesaidmeans, substantially as and for the purpose set forth.

AXEL UNO SRNMARK.

